This kit has been designed for remote control and sensing applications. The kit provides 8 Relay outputs and 4 optically isolated inputs. Easy to use text commands to control the device from any TTY program or write your own software.

Price: $79.95

Special: 10-49 items at $71.96 each

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QK108: Isolated serial Input/ Output Kit V3

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This kit provides 8 relay outputs (mains rated) and 4 optically isolated inputs. It is designed for control and sensing applications. It can be used in various applications including load switching, external switch input sensing, contact closure and external voltage sensing. It is controlled via a serial port using a variety of methods of control software using a set of simple text commands.

Connection to the isolated inputs and relay outputs is via "pluggable type" screw terminal blocks by Dinkle.
Using the serial port has several advantages:1. Fewer wires are required (3 instead of 9 or more needed by the parallel port)2. Serial cables can be a lot longer (up to 100ft) allowing "remote" control.3. Serial ports can be used with any computer and operating system
The kit is constructed on a double-sided, through hole plated printed circuit board (PCB) and fits in a plastic case measuring 140(W) c 110 (D) x 35 (H)mm. Screen-printed front and rear panels are supplied.
The kit requires a 12V DC power supply center positive. A wall adaptor rated at 500mA (minimum) is suitable.
SPECIFICATIONS

RELAYS

Number of relays

8

Type

Form C, SPDT

Contact Capacity

15A 24VDC

Resistive Load

15A 120VAC

10A 240VAC

Contact Capacity

5A 24VDC

Inductive Load

5V 120VAC

5A 240VAC

Maximum allowable voltage

AC 240V

DC 110V

Maximum allowable current

15A

Maximum allowable power force

1800VAC/250W

Minimum applicable load

5VDC 10mA

Relay life (mechanical)

10 million operations

Relay life (electrical/load dependent)

100,000 operations

Operating time

10msec maximum

ISOLATED INPUTS

Number of inputs

4

Type

Polarised, opto-isolated (not TTL/CMOS compatible)

Voltage

5 - 24 VDC

Isolation (min.)

2500V peak

1775V RMS (1 sec.)

CIRCUIT DESCRIPTION
This kit is an extension of our popular QK74, "PC Printer Port Relay Board". The idea was to redesign the PCB to fit into a plastic case and add some inputs as well. At the same time a "latch" was added so that the PC could be switched off without affecting the relays. This proved to be difficult due to the PCs POST (Power On Self Test) function, which would operate and release relays during power up. The easiest solution was to use the serial port.
The brains of the kit is IC1, and 89C2051 microcontroller from Atmel (www.atmel.com). This was chosen because it has the required number of I/O pins and built in serial port. It is preprogrammed to process all commands received via the serial port, control the relays and monitor the inputs.
IC8 provides conversion between TTL and RS232 signals. IC2 is an octal relay driver, ULN2803A, and is used to drive each of the relays. The opto-couplets, IC4-7, are used to provide electrical isolation between the inputs and the rest of the circuitry.
At power-up, all relays are off (released). A reset switch is provided for manually turning off all relays.
Note: during power up relays 1 and 2 momentarily operate. Also, when using the reset switch, these two relays will be operated for as long as the reset switch is pressed. This is due to a characteristic of pins P1.0 and P1.1 of the Atmel microcontroller used.